At present, with the improvement of people's life quality, air conditioners have become necessities for people's daily life; however, the compressor of a common air conditioner is a single-stage compressor, which has a low efficiency in converting mechanical energy into thermal energy and a high energy consumption. With the overall development of energy-saving technologies, air conditioners with dual-stage compressors are available on market; however, there is only one throttle device provided in this type of air-conditioning systems, which is unintelligent in the adjustment of air compensation and evaporation capacity for different operation conditions and frequencies, and leads to a poor system reliability.